methods of scientific research

7/24/2019 Methods of Scientific Research

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Measurement: Scaling,Reliability, Validity

CHAPTER 7


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Ca!ter "b#ecti$es %n&' te caracteristics and !&'er &( te

) ty!es &( scales* n&minal, &rdinal,

inter$al, and rati&+ %n&' &' and 'en t& use te dierent

(&rms &( rating scales and ran-ing scales+ E.!lain stability and c&nsistency and &'

tey are establised+ /iscuss 'at g&&dness&( measures

means, and 'y it is necessary t&establis it in researc+


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ScaleScale ai- esa t&&l ya mecanism y #is - 0ariyea!ne interest - $ariables le - indi$iduals -&distinguis -iya #ata y


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scales Tere are fourbasic ty!es &( scales:

1+ &minal Scale

2+ "rdinal Scale

+ 3nter$al Scale

)+ Rati& Scale

)


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scales Scales ma #ese i um "M3A4 se

RAT3" -i tr( #atay en t& degree of

sophistication increase &ti y+

3TERVA4 ya RAT3" scale - 0ariye$ariable -i in(&rmati&n -& 0iada detailma asil -iya #a s-ta y, 5as c&m!are t& &ter2 $ariables6


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scales 8iada powerful scalesuse -ar - um

a!ni researc 9uesti&ns - 0iada

meaning(ul ans'ers le sa-tay en+


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&minal Scale Nominal scales $ariables -& 4A;E4 -rne - liyye use

&tay en &r in ma 9uantita$e $alues ni &ten,


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&minal Scale >&r example, te $ariable &( gender,

res!&ndents can be gr&u!ed int& two

categories- male and female.

&tice tat tere are no thirdcategoryint& 'ic res!&ndents '&uld

n&rmally (all+

@


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&minal Scale &minal scaling se asil &nay 'ali in(&

se um a!ne sam!le res!&ndents

MA4ES &r >EMA4ES Bage ni-al s-te en,


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"rdinal Scale"rdinal scale $ariables -& categ&ri0e -r - DDDDDai-meaning(ul 'ay ma "R/ER bi -arta y.

1

"rdinalF is easy t&remember because iss&unds li-e G&rder


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"rdinal ScaleTe !re(erence '&uld be ran-ed

5 (r&m best t& '&rse &r (r&m rst

t& last6 and numbered as 1, 2, ,and s& &n+

11


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12

3nter$al Scale

Interval scales ese numeric scales en #inma umen na sir( $alues -a &rder !ta &ta ybul-ay Values - darmiyan e.act dierence b

!ta &ta y+

Te classic e.am!le &( an inter$al scaleis Celsius temperature & TIM because te

dierence bet'een eac $alue is te same>&r e.am!le, te dierence bet'een and degrees is a measurable1 degrees, as is te dierencebet'een @ and 7 degrees+ Time isan&ter g&&d e.am!le &( an inter$alscale in 'ic te increments are

-n&'n, c&nsistent, and measurable


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E.am!le a 3ndicate te e.tent t& 'ic y&u

agree 'it te (&ll&'ing statements

as tey relate t& y&ur #&b, by circlingte a!!r&!riate number against eac,using the scale given !elow.

str&ngly disagree 1, /isagree 2

eiter Agree &r /isagree Agree ), Str&ngly Agree +

1


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E.am!le a 5C&nt+6Te (&ll&'ing &!!&rtunities &ered

by te #&b are $ery im!&rtant t&

me:

1)

3nteracting 'it&ters

1 2 3 4 5

Jsing a number &(

dierent s-ills

1 2 3 4 5

C&m!leting a tas-(r&m beginning t&end

1 2 3 4 5

Ser$ing &ters 1 2 3 4 5


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E.am!le a 5C&nt+6 Su!!&se tat te em!l&yees circle te

numbers , 1, 2, ), and (&r te $e items+

Temagnitude of di"erence

re!resentedby te spacebet'een !&ints 1 and 2 &nte scale is the sameas te magnitude &(dierence re!resented by te s!acebet'een !&ints ) and , &r bet'een any

&ter t'& !&ints+ Any number can be addedt& &r subtracted (r&m te numbers &n tescale, still retaining te magnitude &( tedierence+

1


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E.am!le a 5C&nt+6 3( 'e add t& te $e !&ints &n te

scale, te inter$al scale 'ill a$e

te numbers 7, @,++, 11 5 instead&( 1 t& 6+

Te magnitude of the di"erence

bet'een 7 and @ is still the sameas te magnitude &( te dierencebet'een and 1+

1


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1717

E.am!le b

Circle te number tat re!resents y&ur (eelings at tis!articular m&ment best+ Tere are n& rigt &r 'r&ng ans'ers+Please ans'er e$ery 9uesti&n+

1+ 3 in$est m&re in my '&r- tan 3 get &ut &( it

I disagree completely 1 2 3 4 5 I agree completely

2+ 3 e.ert mysel( t&& muc c&nsidering 'at 3 get bac- in return


+ >&r te e&rts 3 !ut int& te &rgani0ati&n, 3 get muc in return



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Rati& Scale In addition to possessing the

qualities of nominal, ordinal, and

interval scales, a ratio scale als&a$e an abs&lute 0er&+


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Rati& Scale

1


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Rati& ScaleTe ratio scaleis te most

powerful&( te (&ur scales

because it as a uni#ue $eroorigin5 n&t an arbitrary &rigin6+

Te dierences bet'een scales are

summari0ed in te ne.t >igure+

2


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Te dierences bet'een

scales

21


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Pr&!erties &( te >&ur

Scales


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2

/e$el&!ing Scales Te four types of scalestat can be used t&

measure te &!erati&nally dened dimensi&nsand elements &( a $ariable are:

Nominal, %rdinal, Interval, and atioscales+

3t is necessary t& e.amine the methods ofscaling5assigning numbers &r symb&ls6 t&elicit te attitudinal responses&( sub#ectst&'ard &b#ects, e$ents, &r !ers&ns+


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2)

/e$el&!ing Scales

Categories of attitudinalscales: 5n&t t& be c&n(used 'it

te (&ur dierent types of scales6Te atingScales

Te an'ingScales


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/e$el&!ing Scales

ating scalesa$e se$eral res!&nsecateg&ries

and tey are used t& elicit res!&nses'itregard t& te &b#ect, e$ent, &r !ers&nstudied+

an'ing scalesma-e c&m!aris&ns bet'een&b#ects, e$ents, &r !ers&ns and elicit te!re(erred c&ices and ran-ing am&ng tem+

in um'ers


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2

Rating Scales

Te (&ll&'ing ratingscalesare&(ten used in organi$ational

research+

1+ /ic&t&m&us scale

2+ Categ&ry scale

+ 4i-ert scale

)+ umerical scale


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2@

1./ic&t&m&us Scale

3s used t& elicit a Les &r & ans'er+

5&te tat a nominal scaleis used t& elicitte res!&nse6

E.am!le

/& y&u &'n a car= Les &


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2

2.Categ&ry Scale

3t uses multi!le items t& elicit a singleres!&nse+

E.am!le


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3.4i-ert Scale

4i-ert Scale e.amines &' str&nglysub#ects agree &r disagree 'it

statements &n a *!&int scale as(&ll&'ing:

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNStr&ngly eiter Agree Str&ngly

/isagree /isagree &r /isagree Agree Agree 1 2 )

NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN

aa

n,

&ti

Tis is an Interval scale


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1

4.Semantic /ierential Scale


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2

5.umerical Scale

3s similar t& te semantic dierentialscale, 'it te dierence tat numbers

&n a * !&ints &r 7*!&ints scale are!r&$ided, as illustrated in te (&ll&'inge.am!le:

H&' !leased are y&u 'it y&ur ne' #&b=

E.tremely E.tremlely

!leased ) 2 1 dis!leased

al

- is&intsd


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6.3temi0ed Rating Scale

A *!&int &r 7*!&int scale is !r&$ided (&r eacitem and te res!&ndent states te a!!r&!riatenumber &n te side &( eac item+ Tis uses an

Interval *cale+ E.am!le 75i6 Res!&nd t& eac item using te scale bel&', and indicate

y&ur res!&nse number &n te line by eac item+ 1 2 ) Very unli-ely unli-ely neiter li-ely $ery li-ely

unli-ely n&r li-ely********************************************************************************3 'ill be canging my #&b in te near (uture+ ********

s t-&te

er&ta y

a neutral !&int+


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)

7.>i.ed &r C&nstant SumScale

Te res!&ndents are as-ed t& distribute agi$en number &( !&ints acr&ss $ari&usitems+

E.am!le :3n c&&sing a t&ilet s&a!, indicate teim!&rtance y&u attac t& eac &( te (&ll&'ing $e as!ectsby all&tting !&ints (&r eac t& t&tal 1 in all+

>ragrance ***** C&l&r *****

Sa!e ***** Si0e ***** NNNNNNNNN T&tal !&ints 1

Tis is m&re in te nature &( an ordinal scale+


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8.Sta!el Scale

Sta!le Scale measures !oth thedirection and intensity&( te attitude

t&'ard te items under study+ Techaracteristic of interestt& te studyis !laced at te centerand a

numerical scale ranging, say (r&m t&, &n eiter side &( te item asillustrated in te (&ll&'ing

cti&n &r

,

elementce -iyan& sidele r-a

* 1


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E.am!le @: Sta!el Scale

E.am!le State &' y&u '&uld rate y&ur su!er$is&rs abilities 'it

res!ect t& eac &( te caracteristics menti&ned bel&', by

circling te a!!r&!riate number+

2 2 2

1 1 1

Ad&!ting m&dern Pr&duct 3nter!ers&nal

Tecn&l&gy 3nn&$ati&n S-ills * 1 * 1 * 1

* 2 * 2 * 2

* * *


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9.Kra!ic Rating Scale

A gra!ical re!resentati&n el!s teres!&ndents t& indicate &n tis scale

teir ans'ers t& a !articular 9uesti&n by!lacing a mar- at te a!!r&!riate !&int&n te line, as in te (&ll&'ing e.am!le:

ical

ta

ic!er!er


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@

Kra!ic Rating Scale

E.am!le "n a scale &( 1 t& 1, &' '&uld

y&u rate y&ur su!er$is&r=

5

1

10


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10.C&nsensus scale

Scales are als& de$el&!ed by c&nsensus, 'ere!anel &( #udges selects certain items, 'ic in its

$ie' measure te rele$ant c&nce!t.


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)

Ran-ing Scales

an'ing scalesma-e c&m!aris&nsbet'een &r am&ng &b#ects, e$ents, &r!ers&ns and elicitte !re(erred c&icesand ran-ing am&ng tem+

Le bi & s-ta y - #& sa'al !&ce gye

en Ran-ing scales un - e.act clues naden+

+ ,product lines wali example


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)1

Ran-ing Scales

E.am!le 1

Tere are ) !r&duct lines, te manager see-sin(&rmati&n tat '&uld el! decide 'ic !r&duct

line s&uld get te m&st attenti&n+ Assume:

B &( res!&ndents c&&se te 1st !r&duct+

2B &( res!&ndents c&&se te 2nd !r&duct+ 2B &( res!&ndents c&&se te rd !r&duct+

2B &( res!&ndents c&&se te )t !r&duct+

1B


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)2

Ran-ing Scales

Te manager cannot concludetat te rst!r&duct is te m&st !re(erred+


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)

>&rced C&ice

Te (&rced c&ice enablesres!&ndents t& ran- &b#ects

relati$e t& &ne an&ter, am&ng tealternati$e !r&$ided+ Tis is easier(&r te res!&ndents, !articularly i(

te number &( c&ice t& be ran-edis limited in number+

ndents -&

riye-r s-en+

0iada


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))

>&rced C&ice

E.am!le 11 Ran- te (&ll&'ing ne's!a!ers tat y&u

'&uld li-e t& subscribe t& in te &rder &(

!re(erence, assigning 1 (&r te m&st!re(erred c&ice and (&r te least!re(erred+

Q------- Q---------

Q----

!

Q-----------

"

Q--------#

$

%


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)

K&&dness &( Measures

3t is im!&rtant t& ma-te instrument tat 't& measure a !articulais accurately measu$ariable, and 'e are ameasured the conce

'e set &ut t& measure


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)7


H&' can 'e ensure tmeasures de$el&!edreas&nably g&&d=

>irst an item analysres!&nses t& te 9ueta!!ing te $ariable

Ten te relia!ilityvalidity&( te measestablised+

%ese ensure -rna y - ume #& measures de$el&! -iyeHen '& g&&d en.

1.3tem analysis main $ariables seRelated #& 9uesti&ns -iye #atayJn - res!&nses -a anaylysis -iyaata y.

2.Pr Reliablity and ValidityEstablis -i #ati y.


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)@

3tem Analysis

1.3tem analysis is liye -iya #ata y taa - !ta cal #aye - #&instrument bnaya gya y '&& accurate y ya ni.

2.Har item -i ability de-i #ati y - '& '&& ig sc&re &rl&' sc&re gr&u!s -& dierentiate -r ri y ya ni.

3.3s - bad ig sc&re &r l&' sc&re gr&u!s - means -a T*VA4JE - 0ariye test -iya #ata y ta - signicant dierences-aa !ta lag s-e&

4.3s - bad #in items -i T*VA4JE 8iada &ti y un -&instrument ma include -rlia #ata y

5.Js - bad REA43;343TL - liye test -iya #ata y &r !r$alidity establis -i #ati y.

cy

e


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Reliability

elia!ilty me ye btati y - instrument -is adt- unbiased y+ "r reliability ensure -rti y -measurement c&nsistent & acr&ss time and andacr&ss $ari&us items &( te instrument+


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Stability

Ability &( a measure t& remain te same &$ertime+

Test3etest elia!ility:Te reliability c&e(cient&btained 'it a re!etiti&n &( te same measure &n asec&nd &ccasi&n+

4arallel-orm elia!ility: Res!&nses &n t'&

c&m!arable sets &( measures ta!!ing te samec&nstruct are igly c&rrelated+

@)

3 l C i


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72

3nternal C&nsistency

3nternal C&nsistency &( Measuresisindicati$e &( te &m&geneity &( te items inte measure tat ta! te c&nstruct+ Inter-item Consistency Reliability:Tis is

a test &( te c&nsistency &( res!&ndentsans'ers t& all te items in a measure+ Tem&st !&!ular test &( inter*item c&nsistency

reliability is te Cr&nbacs c&eciental!a+

*plit-1alf elia!ility:S!lit*al( reliabilityreects te c&rrelati&ns bet'een t'& al$es

&( an instrument+

a

i measureindicate -rti


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2

Validity

5aliditytests s&' &' 'ell aninstrument tat is de$el&!ed measures teparticular conceptit is intended t&measure+ 5alidityis c&ncerned 'it'eter 'e measure te rigt c&nce!t+

*everal types of validity tests are used t& testte g&&dness &( measures:

content validity6

criterion-related validity6

construct validity+


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C&ntent Validity

Content validityensures tat te measureincludes an ade#uateand representativeset &( items tat ta! te concept.

Te m&re te scale items re!resent ted&main &( te c&nce!t being measured, tegreater te c&ntent $alidity+

3n &ter '&rds, content validityis a

(uncti&n &( how wellte dimensionsandelements&( a c&nce!t a$e beendelineated+


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)

Criteri&n*Related Validity

Criterion-elated 5alidityis establised'en te measure dierentiates indi$iduals&n a criteri&n it is e.!ected t& !redict+ Tis

can be d&ne by establising 'at is calledconcurrent validity&r predictivevalidity+

Concurrent validityis establised 'en

te scale discriminates individuals'&are -n&'n t& be dierent tat is, teys&uld sc&re dierently &n te instrumentas in te (&ll&'ing e.am!le+


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Criteri&n*Related Validity

E.am!le 12

3( a measure &( wor' ethicis

de$el&!ed and administered t& a gr&u!&( 'el(are reci!ients, te scale s&ulddierentiate t&se '& are entusiasticab&ut acce!ting a #&b and glad &( a

&!!&rtunity t& be & 'el(are, (r&m t&se'& '&uld n&t 'ant t& '&r- e$en 'en&ered a #&b+


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E.am!le 12 5C&nt+6

T&se 'it high wor' ethic values'&uldn&t 'ant t& be &n 'el(are and '&uld as- (&rem!l&yment+ T&se '& are l&' &n '&r-etic $alues, migt e.!l&it te &!!&rtunityt& sur$i$e &n 'el(are (&r as l&ng as!&ssible+

3( !oth types of individualsa$e tesame score&n te '&r- etic scale, tente test '&uld not !e a measure&( '&r-etic, but &( s&meting else+


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7

C&nstruct Validity

Construct 5aliditytesties t& &' 'ell te results&btained (r&m te use &( te measure t tete&ries ar&und 'ic te test is designed+ Tis isassessed tr&ug convergentand discriminantvalidity+

Convergent validityis establised 'en tesc&res &btained 'it t'& dierent instrumentsmeasuring te same c&nce!t are igly c&rrelated+

7iscriminant validityis establised 'en, based&ntheory, t'& $ariables are !redicted t& beunc&rrelated, and te sc&res &btained by measuringtem are indeed em!irically (&und t& be s&+


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@


8oodness of Measuresis establisedtr&ug te dierent -inds &( $alidity

and reliability+ Te results &( any researc can &nly be

as g&&d as te measures tat ta! tec&nce!ts in te te&retical (rame'&r-+

Ta!le 9./summari0es te -inds &($alidity discussed in te lecture+


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Validity

methods of scientific research

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